If using a store-bought pastry crust, pre-bake according to package instructions; set aside to cool slightly. If making your own, be sure to prebake the crust.

For the filling: Add 1 cup blueberries and 1/2 cup water to a medium-size saucepan; cover and bring to a boil. Meanwhile, whisk together cornstarch and 2 tablespoons water and set aside.

When the blueberries have come to a boil, reduce the heat and simmer, stirring, for 3 to 4 minutes or until the blueberries burst and the juices begin to thicken. Add the cornstarch mixture, sugar, lemon juice, and salt. Simmer for a minute or until the mixture becomes thick. Immediately remove from the heat and quickly fold in butter and the remaining 3 cups of blueberries.

Spoon the blueberries into the baked crust and allow to sit at room temperature for at least 2 hours or refrigerate until set. When slicing, the blueberries will remain juicy but will not flow out of the crust. Serve with whipped cream or vanilla ice cream.